... If you are using a non-multilib profile, you should not emerge grub, but instead you should emerge grub-static.
If you plan to use a non-multilib profile and you have disabled IA-32 emulation in your kernel, then you should use lilo.

In reality Syslinux seems a better choice though; it's simple to setup and the configuration is a breeze compared to the competition.

I'd have looked at the arch wiki again and tried to work out where I went wrong.
If you go further and combine syslinux with systemd the results are even better!
However, if you're able to use grub2 (you have IA32 emulation) then sticking with it seems reasonable...

Not sure if this is on the Arch Wiki page (All I could be bothered to do is a quick 'find' for "compression").

Anyway, sys/extlinux does not cope well reading a config file on compressed file systems, so for example if you edit your config again after installing (the install done without compression enabled) or you convert say your ext4 partitions to btrfs and enable compression then later edit the config your next boot will fail. Quickest escape if you fall in this hole is probably to boot up live disk like sysrescuecd, mount the partition and edit the config that way since it wont use the compression mount options by default.

Of course this assumed you have btrfs /boot or /boot on /.

Also, I'll post my config file and the files I needed to copy from /usr/share/syslinux to make it work.